NEW YORK (Reuters Health) - Patients with minimal hepatic encephalopathy (MHE) may have impaired fitness to drive a car, according to a report in March issue of Hepatology. The authors therefore recommend that patients with liver cirrhosis should be tested for MHE.

"It has been suggested that the ability to drive a car is impaired in patients with cirrhosis of the liver and MHE," Dr. Christian Wein, of the University of Hamburg, Germany, and colleagues write. "However, the only study using an on-road driving test did not reveal such an impairment."

In a prospective, controlled study, the researchers assessed 274 consecutive patients with liver cirrhosis for MHE and the ability to drive a car. Three psychometric tests were used to diagnosis MHE and the subjects' driving performance was evaluated using a standardized on-road test designed for patients with brain impairment.

Forty-eight patients were included in the study--14 with MHE and 34 without MHE. A control group included 49 subjects in a stable phase of chronic gastroenterological diseases with normal liver findings.

Compared with cirrhotic patients without MHE and controls, the total driving score was significantly reduced in patients with MHE (p < 0.05). Significant differences between those with and without MHE were observed for adaptation to the driving situation, cautiousness, and handling the car. Significant differences were also found in specific driving actions, such as following road signs, paying attention to bicyclists and pedestrians, and following traffic rules.

The instructor had to intervene in 11 patients. An intervention was nearly 10 times as likely to be necessary in cirrhotic patients with MHE versus cirrhotic patients without MHE (p = 0.008). No significant differences in any driving category or specific driving action were observed between cirrhotic patients without MHE and controls.

"MHE is a condition that may diminish the ability to drive," Dr. Wein and colleagues conclude. "As a consequence, we feel justified in endorsing surveillance and treatment of these patients but are not yet [ready] to conclude that all of them are unfit to drive."